Mrs. Quayle objected to being parted from Una. She objected vigorously—vigorously, at least, as compared to her usual manner of taking things. She complained that guarding the baggage in a strange country, where it was impossible to make even her simplest wants intelligible, was not the sort of thing she was there for. But she could not turn Una from her purpose; nor was it any easier, once his consent was given, to move Leighton to a reconsideration of the matter. Only one thing was left for her to do. If she wished to keep within reach of Una she would have to accompany her on the expedition—“the picnic,” as Leighton grimly called it. She hated to do this, but, as solicitude for Una was stronger than concern for her own safety, she had ended by tremblingly begging to be of the party.

“Let her come,” said Miranda derisively. “It will not be for long time.”

So Mrs. Quayle, much as she hated adventures, got what she wanted.

Early next morning, mounted on mules and carrying their supply of provisions neatly packed in hampers, they reached Lake Guatavita. Judging by appearances, one would say that they were after nothing more serious than a day’s outing. The air was crisp and sparkling, of that crystal clearness peculiar to Andean altitudes. The lake laughed in the sunlight; whatever there was of gloomy legend connected with it slumbered beneath its silvery surface. Even the timorous felt the joy of the place and indulged in hopes of high adventure. Miranda was in the best of humor; Leighton, although maintaining his reserve, relaxed something of his usual severity; while the rest of the party was in high spirits, showing scarcely anything of the mental and physical strain to which they had been subjected during the last twenty-four hours. Only Una appeared anxious. Raoul Arthur, the more she saw of him, disquieted her. She disliked him intensely, she could not tell exactly why. He was assiduous in his regard for her comfort, but, in spite of his outward friendliness, she was haunted by certain hints that had come to her from David, hints that made of Raoul, in some inexplicable way, an active enemy to the man she loved. She was suspicious of him. His presence on the expedition that had David’s rescue for its purpose made her twist everything he did into something treacherous, of danger to all of them. Her uncle, apparently, did not share her feeling. On the contrary, he seemed to rely more and more on Raoul for advice and direction in carrying out the project upon which he was engaged, and thus there grew up between the two men a confidence that Una, had she tried, would have been unable to shake.

Andrew, of course, still smarting from the experience of two days before, could not be expected to make so speedy a return to the scene of his adventure without some trepidation. But whatever sensations thrilled his susceptible heart, he put on a brave front and did not flinch from the part he was expected to take in the expedition. There was that dreadful lake, there the wall of rock he had described, and there the inconspicuous opening to the tunnel from whose hidden dangers he had been so mysteriously rescued—he faced it all and braced himself for the inevitable explanations. But his knowledge of the place was far less than Raoul’s.

“It was through this opening to Mr. Parmelee’s tunnel that we entered upon the excavation by which we hoped to drain the lake three years ago,” he remarked.

From an engineering point of view the statement was mystifying because the opening of the tunnel was almost on a level with the surface of the lake. Thus, it was difficult to see what would have been gained had the waters of the latter been diverted into the tunnel. It was explained, however, that an intersecting tunnel at a very much lower level furnished the desired outlet, and the miners had planned to connect with this. As Leighton and the rest were not concerned in these bygone matters, the abortive attempts of the mining company to use this subterranean passage in the mountain was not traced out in detail. Time was urgent; there was no telling how long they might be in the tunnel. If they wanted to avoid making a night of it they would have to hurry.

Unloading the mules, therefore, of their provisions, and leaving these melancholy animals in the care of two peons who had come with them from Bogota, the picnickers equipped themselves for their adventure—that is, they fastened the miners’ lamps to their hats. In the case of the men this was not difficult. But Mrs. Quayle’s extraordinary headgear, architecturally deceptive and insecure, proved so hopelessly difficult that its estimable owner was forced to do without the adornment of tin and kerosene provided for her. The more stable bit of millinery worn by Una was tractable enough, and with her lamp attached firmly to her gray felt hat she looked the part she expected to play.

The opening to the tunnel was much as Andrew had described it, an inconspicuous, narrow rift at the base of a great wall of rock. In nine cases out of ten it would pass unnoticed; so small an aperture, concealed by bushes and trailing vines, was safe from the most inquisitive travelers. That so timid a person as the schoolmaster had discovered (no one took seriously his tale of the togaed and sandaled stranger) and forced his way through this opening caused no end of wonder. To accomplish the same feat drew forth many a groan from the corpulent Leighton and Miranda. As for Mrs. Quayle, what with the squeezing and tugging needed to gain an entrance into the region of terrors beyond, and anxiety lest some of her jewelry might be lost in such strenuous effort, that good lady came dangerously near a condition of hopeless panic. Undoubtedly she would have abandoned the expedition then and there had it not been for the jeers of Miranda who assured her she was developing symptoms that called for a generous dose of his infallible pills. Such a goad would electrify the stubbornest of mules and a series of desperate struggles brought Mrs. Quayle victoriously through the tunnel’s entrance.

This first step in their subterranean travels surmounted, the explorers, having lighted their lamps, found themselves in a spacious rock chamber, the walls of which rose above them to a majestic height. Andrew, especially, was amazed at what he saw, declaring that it was all quite different from his first experience in the same place. When it was remembered, however, that on this former occasion the schoolmaster had only the feeble glimmer of light that found its way through the opening of the cave to show him where he was, the difference between his two impressions was not surprising. But it puzzled his companions to choose the route they were to follow in their explorations. Here Andrew could not help them. Two passages were discovered leading from the chamber in which they stood. One went straight ahead, offering a fairly easy, unobstructed path to the explorer. The other, a branch from the main tunnel, was narrow, strewn with debris of fallen rock, and altogether forbidding in the glimpse that could be had of the first few hundred feet of its course. One feature, however, belonging to this smaller tunnel gave it the preference. But before discovering this feature and making their choice the explorers thought it best to inform themselves, as well as they could, of the character of the cave itself. In this Leighton naturally took the lead, and from his investigations it was concluded that, unlike other caves, the origin of the Guatavita cave was primarily volcanic and due only secondarily to the action of water.

The implement employed by Nature in fashioning her underground caverns is usually water. Some mighty spring, deep within the earth’s bosom, seeks an outlet for its accumulating current. It forces its way through whatever porous layer of rock comes in its path, and by persistent action, occupying ages of time, disintegrates and destroys it altogether. There is left, as a result of the subterranean stream’s activity, a series of tunnels, widening out oftentimes into great rock chambers, and extending, in several well known instances, for many miles. Wherever water is the sole architect the lines that it carves, the forms it molds, are smooth, well-rounded; there are no jagged edges, sharp angles in the fairy palaces and intricate labyrinths that it leaves as specimens of its artistic method. The walls of the Guatavita tunnel, however, were eloquent of a totally different force employed in their making. The marks of an angry Titan were upon them; the Titan of Fire. They told of an elemental tragedy, swift and cataclysmic in its action. The deep scars in their surfaces, the rough crags and pinnacles jutting from them, were the epic characters in which the monster’s struggle for freedom were written down for all posterity to study and wonder at.

Thus, Leighton did not hesitate to attribute an igneous origin to the cave, and it was after a close examination of the earth and pebble-strewn floor that the smaller tunnel was chosen as the best for exploration. There were footprints in both tunnels, but in this one they were more numerous than in the other, where they had been made, according to Raoul, at the time dynamite had been used in the excavations. Comparing these footprints, those in the larger tunnel were evidently from ordinary shoes, while in the smaller they bore the impress of sandals.

“Andrew’s man in the toga is the one we want,” remarked Leighton, a decision that added to Mrs. Quayle’s agitation and did not appear to increase the schoolmaster’s desire for adventure. The discovery of the imprint of sandaled feet, however, changed Doctor Miranda’s attitude toward Andrew from banter almost to admiration.

“It is true, what he say, this leetle fellow,” he declared in astonishment. “He follow him here, the sandals—and he is alone. He is brave man, this Parmelee!”

Raoul remained silent and Herran shrugged his shoulders skeptically. After all, it was difficult to believe, on the strength of a mere footprint, that the singular being described by the schoolmaster actually existed and had disappeared, like some wraith, in the depths of the cave.

“That will be a hard path to follow,” said Raoul finally. “I tried it—once.”

“What did you find?”

“Nothing—a dead wall.”

“Mercy!” ejaculated Mrs. Quayle, not catching his meaning.

“There was no danger that I could see,” continued Raoul; “but there was hard traveling, and no result worth the effort.”

“Did you notice these footprints when you were here before?”

“It was the footprints that led me on.”

“I don’t see your footprints here. All these marks are from sandaled feet,” retorted Leighton.

The discovery did not attract attention. It seemed of slight significance to the others; but the savant continued his examination of the ground with redoubled interest. Raoul also showed astonishment at the fact pointed out to him, and at first offered no explanation. Obviously, a footprint in a cave, not subject to effacement by wind or weather, should remain indefinitely, unless destroyed by man or animal. But, curiously enough, the sandal prints were not sufficiently numerous to stamp out all vestige of the prints that must have been made by Raoul in his coming and going through the tunnel—if Raoul had really ever been in this tunnel. So Leighton argued, and the conclusion that Raoul had not been there at all seemed logical. Had he deliberately deceived them—a supposition for which there appeared no motive—or was he himself mistaken in the course he had pursued in his exploration some years ago?

“Well, there it is,” laughed Raoul. “Your reasoning is sound. My footprints ought to be here, but they aren’t. I can’t explain it.”

“It is not worth while,” exclaimed Miranda impatiently, adding not over lucidly, “they take them away.”

“Perhaps Mr. Arthur wore sandals,” suggested Andrew, illuminated by a brilliant idea.

“Whatever happened, Uncle Harold,” said Una, who had ventured into the tunnel some distance ahead of the others, “what difference does it make now? We are losing time from our search—from your picnic, Mrs. Quayle!”

“Picnic!” she shuddered. “How can we picnic with dead walls and mysterious footprints all around us?”

“Good!” exclaimed Miranda in response to Una’s appeal. “The womens always are captains—the mens must follow!”

There being no objection to this way of putting it, Leighton and Raoul gave up the puzzle of the footprints and set out seriously to explore the tunnel.

They soon found, as Raoul said, that traveling here had its difficulties. Huge boulders that took some little dexterity and sureness of foot to get over obstructed the narrow passage. For Una, who showed surprising agility, such impediments were not disconcerting; but Mrs. Quayle found them not at all to her liking. Progress with that bewildered lady was necessarily slow and, in some unusually rough places, had to be made by a system of shoving from behind and hauling from above that kept her in a state of breathless agitation. This was increased by imaginary terrors, chief among which was the constant dread of meeting the apparition described by Andrew, whose story had made a deep impression on her mind.

As a matter of fact Andrew’s man in the toga was not in evidence, except as the occasional imprint of a sandal on the floor of the cave suggested him. But the explorers were too busy surmounting the obstacles with which the tunnel was strewn to heed details that otherwise might have arrested their attention. The sharp edges of the rocky wall played havoc with their clothing, drawing from Miranda, incensed at his own rotundity, a choice series of expletives—fortunately in Spanish—and arousing the wrath even of Mrs. Quayle. After the first five hundred yards, however, the passage widened sufficiently for them to look about and take account of the perils—if there were any—facing them.

The endless vista of rock, hewn in every conceivable shape and lighted dimly by the rays from their lamps, was dispiriting, to say the least. With the passing of the tunnel, however, and its alarming sense of premature entombment, even Mrs. Quayle experienced a faint return of confidence, while the schoolmaster, her companion in misery, began to feel a mild curiosity in the outcome of an adventure for the undertaking of which he had been the unwilling cause. He wondered vaguely to what further depths of this hole in the mountain the more enterprising spirits of the party would lead them.

“I am sure I never came as far as this,” he protested.

“Well, what of that?” demanded Leighton.

“He say he never come here!” crowed Miranda. “Very well, my leetle fellow, you are here now.”

“Yes, but—how far will we go?” he persisted.

“You remember nothing of this?” asked Raoul.

“I—I rather think I stopped in the beginning of the tunnel.”

“But here are the footprints,” said Una eagerly.

“They are made by sandals. I never wear sandals,” said Andrew sadly.

“Of course. They make by the other fellow.”

“By that man who wears a toga?” asked Mrs. Quayle anxiously. “It would be awful to meet him in this place.”

“She is afraid, this old lady—she have nerves!” announced Miranda. “She better go back.”

There being sound sense in the observation, the others stopped to consider it.

“I could never find my way alone through that tunnel,” declared Mrs. Quayle.

As this was quite obvious, something had to be done. No one wished to desert the unfortunate lady; at the same time all, with the exception of Andrew, were anxious to press on without delay. Miranda, in terse Spanish, explained the difficulty to General Herran, who shrugged his shoulders disgustedly, expressing emphatic disapproval of women as explorers.

“We must do something before we go any further,” said Raoul. “There may be a long journey ahead of us.”

“Do you expect it?” asked Leighton.

“I have no idea where we are.”

“That means——”

“We have passed the dead wall.”

“Merciful heavens!” exclaimed Mrs. Quayle, “we are lost!”

“Hardly that,” said Una reassuringly. “It will be easy to go back the way we came. But this cave is too delightful to leave. I never breathed such air.”

There was ample warrant for Una’s enthusiasm. From the stifling atmosphere of the tunnel the explorers had entered a great rock chamber that widened as they advanced, opening up vistas of majestic spaciousness that contrasted strangely with the straitened path they had first followed. Overhead the outlines of a vast arching roof could be dimly made out by the flickering light from the lamps. At either side the dusky walls, with their flanking pinnacles and fantastic gargoyles, suggested the ornate escarpment of some Gothic cathedral. More noticeable even than these architectural features, was the delightful atmosphere, mild, fragrant, invigorating, pervading the great silent spaces. Usually the air in the famous caves familiar to tourists, although pure enough, is chilly and damp, so much so that the explorer is forced to exercise in order to keep warm. Here, on the contrary, one enjoyed the temperature of a perfect day in early summer—a fact that had called forth Una’s praise, and was silently noted by Harold Leighton as one of the novel features of the Guatavita cave.

“Of course we must go on,” Leighton decided impatiently. “If Mrs. Quayle is nervous, she had better wait for us outside.”

“Perhaps I will be only in the way here,” said that lady contritely. “But what will you do without me, Una?”

“I will take her,” interposed Miranda in a chivalric outburst. “Come!” he added, turning unceremoniously to retrace his steps to the opening of the tunnel, a point that could not be far away, although not near enough to be revealed by the light thrown from their lamps.

In spite of the extended area of the subterranean chamber in which they were standing, it was easy to return to the tunnel by simply retracing the path they were on. This path was marked by a depression in the uneven rocky floor across which it was laid. It was fairly smooth and overspread by a fine sand that bore the impress of many sandaled feet. There was no danger of losing one’s way, and the energetic doctor, hurried along so as to spend the least possible time on his self-appointed mission. He did not notice that the terrified Mrs. Quayle, convinced that his invitation concealed a plot to rob her of her jewels, failed to accompany him. The others, amused at his abrupt departure, patiently awaited his return, watching the speck of light made by his lamp bobbing about in the distance. Presently the light disappeared, and they concluded that Miranda had entered the tunnel. But in this they were mistaken. In a few minutes they were startled by an explosive “Caramba!” followed shortly by the apparition of the doctor running towards them, breathless from his exertions, and exploding with mingled wrath and consternation.

“It has gone—lost! I cannot find him!” he shouted in an incoherent torrent of Spanish and English.

“What has gone?” demanded Leighton.

“We are lost! We are lost! The tunnel has gone!”

“Nonsense!”

“It is true! I go there. I not lie. I find the tunnel where we come—and it has gone!”

“Impossible! What did you find?”

“I not find it. It is true! I find there what this fellow say,” he replied, turning savagely on Raoul. “It is—what you call?—one dead wall!”